ceil

Return the smallest integer that is not less than the input x, and return the value in floating-point format.

Interface Definition

C interface:

float ceilf(float x);

double ceil(double x);

long double ceill(long double x);

Parameters

Parameter	Type	Description	Input/Output
x	For ceilf, x is of single-precision floating-point type. For ceil, x is of double-precision floating-point type. For ceill, x is of long double-precision floating-point type.	Floating-point value of the input data.	Input

Return Value

The rounded value of x is returned. x ∈ (-inf, inf)
If the input is +0, the return value is +0.
If the input is -0, the return value is -0.
If the input is ±∞, the return value is ±∞.
If the input is NaN, the return value is NaN.

Dependency

C: "km.h"

Example

C interface:

    // typical usage
    double x1 = 0.0, x2 = -0.0, x3 = 1.5, x4 = -2.5;
    // special handing
    double a = INFINITY, b = -INFINITY, c = NAN;
    // print result
    printf("ceil(0.0) = %.15f\n", ceil(x1));
    printf("ceil(-0.0) = %.15f\n", ceil(x2));
    printf("ceil(1.5) = %.15f\n", ceil(x3));
    printf("ceil(-2.5) = %.15f\n", ceil(x4));
    printf("ceil(INFINITY) = %.15f\n", ceil(a));
    printf("ceil(-INFINITY) = %.15f\n", ceil(b));
    printf("ceil(NAN) = %.15f\n", ceil(c));
    /* 
     * ceil(0.0) = 0.000000000000000
     * ceil(-0.0) = -0.000000000000000
     * ceil(1.5) = 2.000000000000000
     * ceil(-2.5) = -2.000000000000000
     * ceil(INFINITY) = inf
     * ceil(-INFINITY) = -inf
     * ceil(NAN) = nan
     * */

Parent topic: Rounding Functions